docstr: Return whether or not a given name has been defined as an alias
docstr_tok: ["Return","whether","or","not","a","given","name","has","been","defined","as","an","alias"]
code: def is_alias(self, name):
      """Return whether or not a given name has been defined as an alias"""
      return self.get_alias(name) is not None
  
imports: import os
  import re
  import sys
  from traitlets.config.configurable import Configurable
  from .error import UsageError
  from traitlets import List, Instance
  from logging import error
label_desc: Use image node_id 7 for calling the AliasManager obj's underlying member method code with example usage: obj.is_alias(name) and returns: unknown